新型氧化镍超电容器电极材料的研究

使用传统的水解方法制备了氢氧化镍胶体,在300℃下进行热处理后得到具有特殊材料微结构以及表面特性的超细氧化镍材料,电化学方法证明该材料制备的电极具有典型的电容性能,“准电容”比容量达到240F／g以上,优于普通的双电层电容器活性炭电容材料比容量。本文首次提出了电容器的正负极采用不同材料的新技术,有效的解决了电容器工作电位范围相对较窄的不足,并且明显的改善了电容器的大功率放电特性,是一种极具有发展潜力的储能器件。     

纳米氧化镍的超电容性研究

采用柠檬酸盐凝胶热分解工艺制备了比表面积达181m2/g,一次粒子粒径在20nm以下,孔径分布集中在4～10nm之间的纳米氧化镍粉体,其超电容性是由双电层电容和法拉第准电容共同组成,比容量可达80～102F/g,工作电位窗达1.2V,并具有良好的循环稳定性和阻抗特性,这种材料可作为超级电容器的电极材料.     

碳纳米管表面沉积氧化镍及其超电容器的电化学行为

通过催化裂解法制备了碳纳米管并进一步制备了碳纳米管薄膜电极.基于该种材料的超电容器电极比容量达到36F/g.研究了在碳纳米管薄膜基体上使用电化学方法沉积氧化镍的新工艺,制备出碳纳米管和氧化镍的复合电极.电化学测试证明复合电极的比容量提高到52F/g以上且基于这种复合电极的超电容器具有极低的自放电率.     

利用少量氧化镍负载提高活性炭比电容

为提高活性炭电极材料的比电容,本实验采用低浓度碱式碳酸镍溶液对活性炭进行氧化镍表面负载,利用碱式碳酸镍的热解特性,在引入赝电容的同时,减小负载对活性炭原有孔隙结构的影响,从而在引入赝电容的同时较好地保留活性炭的双电层电容.本实验还研究了不同数量氧化镍负载对活性炭孔结构和电化学性能的影响.实验结果表明:氧化镍负载改性后,活性炭在较好保留了原有孔隙结构的基础上,还在孔结构表面均匀负载了大量的纳米级氧化镍,改性后活性炭电极材料引入了赝电容,活性炭的比电容性能得到明显改善,且随着氧化镍负载数量的增多,活性炭比电容性能逐渐提高.     

纳米氧化镍的制备及超级电容性能研究

以NiSO4·6H2O和NaOH为原料,采用常温合成-水热改性-中温焙烧工艺制备了分散性好、平均粒径约为40nm的规则六角片状形貌的氧化镍电极材料.利用循环伏安和恒流充放电对氧化镍制备的电极的电容性能进行了研究,结果表明,NiO电极在KOH电解液中具有良好的超电容特性和循环寿命,在充放电电流为20mA时,NiO电极的比容量达到252F/g.     

金属氧化物超大容量电容器电极材料的研究进展

超大容量电容器是一种介于传统电容器和电池之间的新型储能元件,它比传统电容器具有更高的比电容和能量密度,比电池具有更高的功率密度,因而具有广阔的应用前景.简要介绍了超大容量电容器的储能机理、特点,综述了金属氧化物超大容量电容器电极材料的发展状况,以及改善氧化钌基电容器的方法和廉价材料(如氧化镍、氧化钴、氧化锰、氮化钼等)替代氧化钌电极的研究进展情况,展望了其发展趋势.     

氧化物／活性炭复合电极材料的研究

用醋酸锰和高锰酸钾制备二氧化锰粉末；用氯化钌和氢氧化钠制备水合二氧化钌粉末。以二氧化钌和二氧化锰作为电极材料的活性物质，以活性碳粉末为电极的基础原料制备复合电极，并组装超级电容器单元。用x射线衍射仪和扫描电镜对电极材料进行表征，可得复合电极具有明显的电容特征。在浓度为38％的硫酸电解质溶液中，对复合电极进行电化学性能测试，循环伏安曲线、充放电曲线和交流阻抗特性显示了复合电极材料具有良好的电化学性能。碳，锰复合电极的比容量为128F／g，碳/锰/钌复合电极的比容量为266F/g。当二氧化钌和二氧化锰在电极中质量比各占20％时，更能发挥活性物质的作用，由该电极材料组成的超级电容器具有理想的电容特性。     

超级电容器用石墨烯极片的制备和性能

以石墨粉为原料,通过简便的氧化还原法制备了石墨烯。将石墨烯极片在有机电解液体系中组装成超级电容器。利用XRD、SEM对制备的石墨烯电极进行物相和形貌分析。采用恒电流充放电、循环伏安和交流阻抗对所制备超级电容器的电容性能进行了研究。结果表明,石墨烯电极超级电容器比天然石墨制备的超级电容器的比电容有了明显的提高;在电流密度为200mA/g,电压区间为1.25~2.5V下循环888次后比电容保持在45.5F/g,容量保持率在85.5%,表明石墨烯材料制备的电容器具有较好的充放电循环性能。     

溶胶-凝胶技术制备超级电容器金属氧化物电极材料的研究进展

金属氧化物电极材料兼有双电层电容和法拉第准电容,溶胶-凝胶技术制备金属氧化物电极材料可有效地提高比容量且制备的材料纯度高、工艺简单等,使超级电容器性能得到显著的提高,引起了许多研究者的广泛关注。综述了超级电容器的特征、应用范围,并详细地介绍了溶胶-凝胶技术制备金属氧化物电极材料的优点和存在的问题及研究进展情况,为促进新型储能电极材料的研究提供科学参考。     

原位沉淀-焙烧法制备NiO/P-CNT复合材料及其电容性质

以聚吡咯衍生的碳纳米管作为载体,通过原位沉淀-焙烧相结合,合成了新型的氧化镍/聚吡咯衍生碳纳米管(NiO/P-CNT)复合材料。采用粉末X射线衍射、热重、能谱、扫描电镜、透射电镜、循环伏安以及恒流充放电测试对样品进行表征和分析。结果表明,须状氧化镍均匀的负载在聚吡咯衍生的碳管表面,构成了具有三维网络结构的复合物。基于这种特殊结构的优势,该复合物在电流密度为2A/g下的比电容为382F/g,NiO在复合物中电容贡献为441F/g,而NiO的比电容为351F/g。经过400圈充放电后,复合物的比电容保持在90%以上,而NiO的容量保持率为82.6%。因此,该复合电极材料较NiO具有更高的比电容和更好的循环特性。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.